Synthesis of 3,4-dihydropyrimidin-2(1H)-one and 3,4-dihydropyrimidin-2(1H)-thione derivatives from aldehydes, 1,3-dicarbonyl derivatives and urea or thiourea using granite and quartz as new, natural and reusable catalysts. Some of the 3,4-dihydropyrimidin-2(1H)-thione derivatives were used to prepare new heterocyclic compounds. The antimicrobial activity of selected examples of the synthesized compounds was tested and showed moderate activity.

A new series of thiazolo[3,2-a]pyrimidine bromide salt derivatives 7a–d were synthesized from 3,4-dihydropyrimidinethione precursors. The target compounds were fully characterized by 1D- and 2D-NMR, high resolution ESI-MS/MS and single crystal X-ray diffraction analysis, which confirmed a regioselective 5H cyclization of the dihydropyrimidinethiones. All target compounds were evaluated in vitro as human acetylcholinesterase (hAChE) inhibitors via an Ellman-based colorimetric assay and showed good inhibition activities (better than 70% at 10 µM and IC50 values in the 1 µM range). Molecular docking simulations for all target products into hAChE were performed and confirmed strong binding to the enzyme. These results provide a promising and new starting point to improve acetylcholinesterase inhibitors and explore novel treatment options against Alzheimer’s disease.

3-Oxo-N-{4-[(pyrimidin-2-ylamino)sulfonyl]phenyl}butanamide 3 was condensed with (DMF-DMA) in refluxing dry dioxane to yield branched structure 4 not its linear isomeric 5. Compound 4 readily reacted with active methylene to yield compounds 8a-c, 14, 17 and 20 respectively. Also enaminone 4 reacted with phenyl hydrazine giving 24 and 25. In contrast, when compound 4 reacted with hydrazine hydrate in the same experimental conditions pyrazole derivative 27 was obtained. Furthermore, condensation of anilide 3 with triethylorthoformate in refluxing acetic anhydride afforded the ethoxy methylene derivative 28. On the other hand, compound 28 was reacted with active methylene reagents, and hydrazines to afford the products identical in all respects (mp., mixed mp., and spectral data) with those corresponding to compounds 6-27 respectively. Similarly, compound 3 was reacted with hydrazine hydrate to afford the reaction product 29. Also, compound 3 reacted with cyanoacetamide in refluxing ethanolic pipridine solution to yield the pyridine derivative 30. Finally, 3 reacted with hydroxylamine hydrochloride in refluxing ethanol/sodium acetate solution to yield the acyclic oxime derivative 31.

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The imidazolones (III) are synthesized by amination of the oxazolones (I).

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Aus den Oxazolinonen (I) werden die Imidazolinone (II) hergestellt, die in die Derivate (III)‐(X) übergeführt werden.

Fused pyridine derivatives R 0450Reactions of Some Active Carbonyl Compounds with 4-Aryl-1,6-diamino--2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile Derivatives. -The synthesis of a variety of alkylideneaminopyridone, triazolopyridine and pyridotriazepine derivatives is achieved by condensation of diaminopyridine (I) with reactive carbonyl compounds under acidic or alkaline catalysis. -(HARB, A. A.; Chem.